Power amplifiers are typically active elements that can magnify an input signal to yield an output signal that is significantly larger than the input signal. Many types of power amplifiers exist and there are many ways to create power amplifiers. For example, some power amplifiers can be created using heterojunction bipolar transistors (HBT).
Many HBT power amplifiers use a diode stack bias configuration. In some such configurations, the diode stack bias configuration exhibits sensitivity to the device beta, which can result in substantial quiescent current variation of the amplifier. Further, the variation of quiescent current may impact performance parameters and may degrade product yield.